The present invention relates to a stent graft with a hollow cylindrical body and a sleeve catheter, wherein the body has at least one self-expanding stent and a prosthetic material, wherein the body, in a compressed state, has a circumference that is smaller than a circumference of the body in an expanded state.
Stent grafts of this kind are well known in the prior art. These are in the form of a medical implant which is inserted into hollow organs, for example blood vessels, of a patient in order to keep open any constrictions that have been caused there by disease and, by so doing, to maintain the flow of blood. Moreover, stent grafts are used for the intravascular treatment of aneurysms, dissections and other specific lesions. The stent graft usually has a hollow cylindrical shape with a longitudinal extent, such that blood is able to flow through the hollow space of the stent graft in the implanted state.
However, in order to ensure that such a stent graft remains effective for the period of treatment in the blood vessel of a patient, it is necessary for the stent graft to be fixed in position at the site that is to be treated. This is permitted by a sufficiently large contact area between the jacket surface of the stent graft and the vessel wall, wherein the stent graft has to lie with its jacket surface snugly on the vessel wall.
In the prior art, therefore, stent grafts are known which have a self-expanding stent and are therefore compressible and expansible again. They can therefore adopt at least two states, namely a compressed state and an expanded state. For implantation, the stent graft is initially compressed in the radial direction such that the diameter of the hollow cylindrical body is reduced at least to the extent that the latter is insertable into the blood vessel of the patient. In order to produce the compressed state, the stent graft is introduced into a sheath designated as a sleeve catheter. The sleeve catheter for this purpose has a circumference that is smaller than the circumference of the stent graft in the expanded state. In the compressed state, the stent graft, together with the sleeve catheter enclosing it, is inserted into a blood vessel and then positioned at the pathological site, it being possible to monitor the position of the stent graft with the aid of X-ray markers. Once the desired position or orientation of the stent graft is reached, the sleeve catheter is withdrawn, as a result of which the stent graft is released and is able to expand. On account of the self-expansion property of the stent, the stent graft stretches open in the blood vessel. As a result of the pressure force between the stent graft and the vessel wall, the stent graft remains fixed in place at the desired position. The blood vessel can thus be kept open and the flow of blood maintained.
In the prior art, for example, stent grafts are known in which the stent is formed as a wire structure, which is responsible for the self-expansion property of the stent. The wire structure is normally made of metal or plastic and is moreover enclosed by a prosthetic material, which is secured on the wire structure. The prosthetic material can be composed of textile material, for example a woven polyester fabric impervious to blood. The biocompatibility of such materials means that the contact between the vessel wall and the expanded stent graft is free of complications.
DE 103 35 948 B3 discloses a stent graft with an aforementioned stent, wherein the stent in the expanded state is able to be compressed again with the aid of a thread after the stent graft has been inserted into a blood vessel of the patient. This therefore permits the removal of a stent graft that has already been inserted into a blood vessel.
WO 2011/063972 A1 and US 2007/0100427 A1 disclose a similar stent graft in which, with the aid of one or more threads, the diameter of the stent graft can be changed after it has been inserted. EP 1 964 532 A2 discloses a further stent graft in which the sleeve catheter can be pulled back in stages.
In all of the aforementioned documents, the sleeve catheter is designed as a separate sleeve tube into which the body of the stent graft is pushed and thereby compressed. However, this has the disadvantage that the compression is made difficult since the person carrying out the treatment has to fold the body of the stent graft up in portions and at the same time insert it into the sleeve catheter until the latter fully encloses the body of the stent graft. Moreover, the withdrawal of the sleeve catheter in order to expand the hollow cylindrical body of the stent graft is associated with frictional forces, on the one hand, between the sleeve catheter and the vessel wall and, on the other hand, between the sleeve catheter and the body of the stent graft. This may, on the one hand, cause damage to the vessel wall and, on the other hand, cause the stent graft to be displaced or twisted from its previously adopted optimal position. The latter scenario necessitates awkward repositioning of the stent graft in the blood vessel.